The systems and methods disclosed herein are related to the art of image rendering devices such as printers and displays. Embodiments will be described in terms of laser-based electrophotographic marking engines, such as those used in printers, photocopiers and facsimile machines. However, embodiments are applicable to other rendering devices, such as those that present image data in raster lines including display devices and other kinds of printers.
By way of background, print quality can suffer from misregistration defects in printing architectures. Image rendering (or printing) processes are physical in nature. That is, image rendering processes rely on physical structures which can influence rendered image quality and consistency. For instance, variation in phosphor quality or density in a cathode ray tube (CRT) or plasma display, light emitting diode (LED) efficiency in an LED display, and/or spatial variation in the light output of a fluorescent back light in a liquid crystal display (LCD) can cause color appearance variations across the surface of a display device. In printing systems, physical alignments, component tolerances, wear and component age can influence the uniformity with which colorants such as inks and toners are laid down across the surface of print media.
Further, in a printer/copying machine where toner is fixed to a sheet, moisture is evaporated by the influence of heat when an image is fixed on a sheet and the sheet is shrunk, or the sheet is stretched by the influence of pressure of the fixing processing. Additionally, sheets may be out-of-skew or out-of-register. Rotation and slanting may occur in the case where printing is carried out using an intermediate transfer member. In that case, a difference in nip balance in an axial direction of a transfer part causes a difference between a direction in which an image is transferred and a traveling direction of a sheet, and the rotation or slanting can occur. When such slanting/rotation occurs, an image printed on the sheet may become trapezoidal or fan-shaped.
In production printers there is a need to perform magnification adjustments to register duplex (i.e., side 1-to-side 2) printing. Process direction Electronic Registration (ER) as practiced in certain products has the resolution of the raster spacing and can suffer from image quality defects for many desirable halftones.
Thus, the exemplary embodiments relate to a new and improved method and apparatus that resolves the above-referenced difficulties and others.